In today's word, henotheism, however, spell-check rejected my spelling of a more common word - worshipping. Is it only one 'p'?
No, say I. But what's the rule?
Fowler's makes the point that it's worshiped and sometimes kidnaped in American English. But I find this exception to the exception of the exception a bit much. Double the last consonant when taking a suffix, except for words ending in p where the final syllable is not stressed, except for worship, kidnap and handicap, except for worship in the US. But not doubling the final letter in these words with a suffix makes the final vowel look like it should be long. I'm with the Brits on this one.
Even here, there are pesky exceptions: ‘worship’, ‘handicap’ and ‘kidnap’ become ‘worshipping/worshipped’, ‘handicapping/handicapped’ and ‘kidnapping/kidnapped’ in standard received British English.